Electrolytic reduction cell

ABSTRACT

IMPROVED ELECTROLYTIC REDUCTION CELL FOR PRODUCING MOLTEN MAGNESIUM METAL AND THE LIKE AND MADE UP OF UNIQUELY AND REMOVABLY ARRANGED OUTER AND INNER SHELLS HAVING A MASS OF THERMALLY RESISTANT MATERIAL INTERPOSED THEREBETWEEN AND WHEREIN THE INTERIOR OF THE CELL IS DI-   VIDED IN AN IMPROVED FASHION INTO FEED AND ELECTROLYTIC CHAMBERS.

May 25, 1971 J. R. PETERSON ELECTROLYTIC REDUCTION CELL 6 Sheets-Sheet 1 Filed Feb. 24, 1969 n I N- HIHMIH INVENTOR. L/OHN IQ. PE r512 SON 477'0R/VEY May 25, 1971 J. R. PETERSON ELECTROLYTIC REDUCTION CELL a Shets-Sheet 2 Filed Feb. 24, 1969 93 Em Nk\ Q. mm mm domv 14?. Peruse/v INVENTOR.

ATTORNEY May 25, 1971 J. R. PETERSON ELECTROLYTIC REDUCTION CELL IN 5 Wm t ST R h w S T 9 E m q v M 6 M d Y B mm 13 m w. w w& 8% N3 3 m& M NE m m M 4M- mun-NI m Q 1| IIA n F NE PM ATTORNEY May 25, 1971 J, R. PETERSON 3,580,835

ELECTROLYTIC REDUCTION CELL Filed Feb. 24, 1969 e Sheets-Sheet 4 day/v 1?, PETERSON INVENTOR. BY fiJW F M HHIH ATIZYFA/EY y 25, 1971 J. R. PETERSON 3,530,335

ELECTROLYTIC REDUCTION CELL Filed Feb. 24, 1969 6 Sheets-Sheet 5 fIIE-A (Joy/v 14?. PETERS ON I NVENTOR.

dTIWE/VEY J. R. PETERSON ELECTROLYTIC REDUCTION CELL May 25, 1971 V Filed Feb. 24, 1969 6 Sheets-Sheet 6 day/v 1?. PETERSON ATTORNEY United States Patent Olfice 3,580,835 ELECTROLYTIC REDUCTION CELL John R. Peterson, Oakland, Calif., assignor to Kaiser Aluminum & Chemical Corporation, Oakland, Calif. Filed Feb. 24, 1969, Ser. No. 801,454 Int. Cl. C22d 3/02, 3/08 US. Cl. 204-243 23 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to an electrolytic reduction cell for producing magnesium metal. More particularly, it relates to an improved electroyltic reduction cell provided with means for holding a fused electrolytic bath containing magnesium chloride of a density less than the magnesium metal produced from the bath and provided with further means for dividing the cell into an electroytic chamber and a feed chamber in such a unique fashion that the electrolytic bath can be periodically replenished without at the same time interfering with the normal production of magnesium metal and appropriate collection of chlorine gas liberated from the bath during operation of the cell.

In the past, electrolytic cells have been provided for producing magnesium from a fused electrolytic bath containing magnesium chloride and having a density less than the magnesium metal liberated from the bath, as exemplified by the US. Pat. 2,880,151 to Dean et al. granted on Mar. 31, 1959, and US. Pat. 2,950,236 to Dean et al. granted on Aug. 23, 1960, One of the principal deficiencies of prior electrolytic cells for producing magnesium was that the cells structure did not lend itself to ready servicing of the cell during the use thereof. The cell structure was also such that it did not effectively separate the electrolytic chamber from the feed chamber, thus often necessitating the use of an anhydrous feed for the cell, which is difiicult and costly to obtain.

SUMMARY OF THE INSTANT INVENTION The primary purpose of the instant invention is to provide an improved electrolytic cell adapted to hold a fused electrolytic bath containing magnesium chloride of less density than the magnesium metal produced from the bath and having unique means for effectively dividing the cell into an electrolytic chamber and a feed chamber in order that the fused electrolytic bath can be periodically replenished through the feed chamber by an appropriate feed mechanism without at the same time interfering with the production of magnesium metal and anhydrous chlorine liberated from the fused electrolytic bath in the electrolytic chamber of the cell during the operation thereof.

BRIEF DESCRIPTION OF THE INVENTION Wtih reference to the accompanying drawings,

FIG. 1 is is a simplified diagrammatic and perspective view of a preferred embodiment of the cell of the instant invention;

FIGS. 2 and 2A when taken together constitute an overall side elevational view, with parts broken away and parts shown in section of the cell of the instant invention;

FIG. 3 is an end elevational view taken along line 33 3,580,835 Patented May 25, 1971 of FIG. 2A, with parts added and other parts broken away;

FIG. 4 is a top plan view taken along line 4-4 of FIG. 2, with parts broken away;

FIG. 5 is an enlarged framgmentary view taken from a position along line 5--5 of FIG. 4.

FIG. 6 is an enlarged fragmentary prespective view taken from a view point generally in the area of line 6-6 in FIG. 2; and

FIG. 7 is an enlarged cross sectional view taken along line 7-7 of FIG. 6.

With further reference to the drawings and particularly FIGS 1-4 thereof, a preferred embodiment of an improved electrolytic reduction cell 10 for producing magnesium metal and the anhydrous baseous chlorine incidental thereto in accordance with the instant invention, generally comprises an open-ended grid-like framework 12 of receptacle-like configuration. An open-ended overall outer metal shell 14 is disposed within the framework 12 and an inner open-ended overall metal shell 16 of roughly H-shaped configuration in plan view is removably disposed within and in spaced relation to the outer shell 14. A uniformly compacted mass of thermal resistant particulate material 18 preferably powdered alumina can be advantageouly interposed between and fill the cavity between the shells 14 and 16. The segments for the overall shells 14 and 16 and framework 12 on each side of a centerline of the cell as well as their associated parts have a like configuration and structure; therefore, a description of one side of the cell will sufiice for both.

Since the alumina 18 is relatively incompressible and since there is a tendency of the inner shell 16 to thermally expand relative to the outer shell 14, suitable resilient means such as tubes can be disposed between the inner and outer shells 16 and 14 so as to compensate for the relative thermal expansion between the shells, thereby preventing fracture of either one of the shells 14 and 16 during operation of the cell 10.

Each of the inner and outer shell segments is preferably made up of weldably interconnected plates of a suitable grade of steel. As indicated in FIGS. 1 and 3-4, the inner shell 16 is comprised of a pair of longitudinally spaced segments or portions 21 that terminate at each end in reduced end sections 20 and 24. The intermediately disposed end or web portion 22 of the inner H-shaped shell 16 is connected to adjacent enlarged portions 21 and the inner shell 16 is flanged outwardly and upwardly at the upper end thereof in the manner illustrated at 26 in FIGS. 2A, 3 and 4.

As indicated in FIGS. 2, 2A, and 4, spaced divider elements 28 are disposed within the overall inner shell 16 adjacent the upper end thereof and extend in a direction generally transverse of the longitudinal axis of the cell 10. The longitudinal ends of each one of the divider elements 28 are connected to and supported by opposed ledges 124 provided in opposed sidewall portions of the inner shell 16 at a reduced end portion 20 or 22 or 24, as the case may be. As will become more apparent hereinafter, the dividing elements 28 advantageously divide the opening of the overall inner shell 16 in to a plurality of feed chambers 32, 34 and 36 and two electrolytic chambers 40 and 40. These chambers 32, 34, 36, and 40- 40 of the inner shell 16 beneath or below the four divider elements 28 and above the bottom of the inner shell 16 are in direct open intercommunication with each other. The flange 26 at the top of the inner shell 16 in conjunction with the four dividing elements 28 supports a series of two upstanding refractory liners 42 and another series of two upstanding referactory liners 44 in interposed relation to the series of three liners 42. A liner 42 circumscribes each of the feed chambers 32, 34 and 36 at the upper portions thereof and a liner 44 circumscribes each of the electrolytic chambers 40 at the upper portions thereof.

During operation of the electrolytic cell 10, the overall inner shell 16 is adapted to receive a predetermined amount of a fused electrolytic bath 46, containing magnesium chloride and having a density less than the magnesium metal liberated from the bath. By virtue of the liberated magnesium metal 48 being of greater density that the bath, it settles out at the bottom of the inner shell 16 where it collects and can be removed in a suitable manner such as by valved piping (not shown) connected to the bottom of the inner shell 14 as indicated in FIG. 2A. The normal surface level of the bath 46 during operation of the cell is preferably disposed between the top and bottom edges of the refractory liners 42 and 44. Each one of the pair of electrolytic chambers 40 is covered at the top thereof and at a distance above the normal surface level of the electrolytic bath 46 by a refractory lined closure element 50.

Each one of the pair of closure elements 50 includes a series of three longitudinally spaced apertures 52 for slidably receiving carbon anodes 54 of generally rectangular shape in transverse cross section. At least one opening 64, see FIG. 2A, is provided in each of the covers 50 for exhausting the gaseous chlorine liberated from above the surface level of the electrolytic bath 46 in the electrolytic chamber 40 associated therewith when the cell is being operated. Similarly, the open ends of each one of the reduced portions 20, 22, 24 of the inner shell 16 is covered by an apertured cover plate 66, thereby enclosing the associated feed chambers 32, 34, 36 at a distance above the normal surface level of the electrolyte 46 disposed therein. Each one of two series of six pairs of cathodes 56 is connected to the inner and outer shells 14 and 16 and disposed in either one of the enlagred portions 21 of the inner shell 16. Each one of several pairs of cathodes 56 in chambers 40 are connected to the inner and outer shells 14 and 16 as well as being disposed along the longitudinal axis of the cell 10 in spaced relation to each other. They are also disposed in a direction transverse to the longitudinal axis of the cell .10 in such fashion that the inner ends of a given pair of aligned cathodes '56 are slightly spaced from each other while being disposed within the opening of the inner shell 16 at an enlarged portion 21 thereof. As indicated in FIGS. 3 and 5, the spaced inner ends of a given pair of aligned cathodes 56 are interconnected by a device 58. The outer ends of a given pair of aligned cathodes 56 extend outwardly of the outer shell 14 for electrical connection to a D.C. source (not shown).

A support assembly 60 attached to the upper end of each one of the three anodes 54 associated with one of the pair of cover elements '50 and is connected to the upper end of the framework 12 for slidably disposing each one of the three anodes 54 within their associated apertures '52 and in spaced and operative relation to adjacent pairs of spaced cathodes 56. Each support assembly 60 can be used to effect electrical connection of its associated anode 54 to a D.C. source (not shown). A water cooling device 62, see FIG. 6, may be attached to an opposed side of a support assembly 60, to maintain the anode 54 at a desired temperature level during operation of the cell 10.

The open-ended grid-like framework 12 is generally comprised of a plurality of spaced I-shaped beams 70, a pair of spaced channel-shaped beams 71, and a plurality of upstanding spaced T-shaped elements 72. The series of spaced I-shaped beams 70 and channel-shaped beams 71 form the bottom of the framework 12. The upstanding T-shaped elements 72 form the opposed end and sidewalls of the framework 12 and are disposed about the sidewall perimeter of the cell 10. The lower ends of certain ones of the T-shaped elements 72 at the opposed sidewalls of the framework 12 are connected to the upper flanged end portions of the I-shaped beams 70, as indicated in FIG. 3.

On the other hand, as depicted in FIGS. l-2, other spaced T-shaped beams 72 are disposed at the end sidewalls of the framework 12 and are somewhat longer than the first mentioned T-shaped beams 72 on the opposed sidewalls thereof. These other spaced T-shaped beams 72 are connected at their lower ends to intermediate portions on the back side of the web of either one of the pair of the channel-shaped beams 71. As indicated in FIG. 2, by virtue of the other T-shaped end sidewall beams 72 being somewhat longer than the first mentioned opposed sidewall beams 72, the upper ends of the end sidewall beams 72 of the framework 12 extend somewhat above the upper ends of the sidewall beams 72 thereof, the purpose of which will be set forth more fully hereinafter.

With reference particularly to FIGS. 1 and 3, it will be observed that the upwardly opening outer shell 14 is generally comprised of telescopically-connected lower and upper sections 74- and 75 disposed within the upwardly facing recess of the framework 12. The lower section 74 includes a series of interconnected steel plates arranged to form a shallow upstanding box-like structure. The lower portion of shell 14 also includes opposed side plates 76 extending the full length of the framework 12 between the end sidewall beams 72 thereof and further includes end plates 78 extending the width of the framework between the inwardly disposed free edges of the web portions of the oppose sidewall beams 72.

The side and end plates 76 and 78 of the lower section 74 are of the same height and the upper edges of all the side and end plates 76 an 78 include a common interconnected flange 80 of angle-shaped configuration that extends in an outward and downward direction about the sidewall perimeter of the framework 12. The flange 80 extends laterally outward a distance shorter than the depth of the web portion of a given beam 72 of the framework 12 as illustrated in FIG. 2. At the point where the flange 80 intersects the web portion of a given beam 72, it is provided with recesses, only one of which is indicated at 81 in FIG. 2, so that the web portion of a given beam 72 can be freely inserted and anchored therein. The common flange 80 at the top of the side and end plates 76 and 78 not only reinforces the same but also facilitates telescoping connection of the upper section 75 to the lower section 74, as will be subsequently described.

A bottom plate 82 extends freely between and is connected to the lower aligned edges of the side and end plates 76 and 78 and is further connected to the top of the beams 70 and 71 forming the bottom of the framework 12. The side and end plates 76 and 78 are connected to the inner free ends of the web portions of the upstanding end and sidewall beams 72 of the framework adjacent the bottom thereof. Thus, the side, end and bottom walls 76, 78 and 82 of the lower section 74 of the inner shell 14 in being connected to the beams 70, 71 and 72 of the framework 12 holds the beams thereof in spaced relation while further rigidifying the framework 12.

A pair of plates 84 at their longitudinal ends extend fully between and are connected at one extremity to the opposed inside surface portions of the end plates 78 of the lower section of shell 14 at each end thereof in such fashion that the plates are inclined in a downward and inward direction at the bottom of the lower section 74 of the inner shell 14. At the same time the opposed longitudinal edges of each one of the pair of plates 84 are connected to spaced intermediate surface portions of a side plate 76 and the bottom plate 82 in order to provide the bottom of the lower section 74 with a configuration that is roughly V-shaped in transverse cross-section. The V-shaped bottom of the lower section 74 of the outer shell 14 not only facilitates centering of the inner shell 16 relative to the outer shell 14 during assembly of the inner shell into the cavity of the outer shell, but also provides for uniform compaction of the mass of powdered alumina 18 disposed between the shells 14 and 16. Reinforcing elements, not shown, can be provided to extend between and be connected to a plate 84 and the underlying end portion of the bottom plate 82.

The upper section 75 of a segment of the outer metal shell 14 is made up of opposed side plates 86 of a length somewhat less than the end plates 78 of the lower section 74 but of a height corresponding to the height of the side plates 76 of the lower section 74. The side and end plates 86 and 88 of the upper section 75 are interconnected together in a suitable manner, such as by welding, to form a tubular upper section that is adapted to overlappingly engage the upper edge of the lower section 76 about the periphery of the cell as illustrated in FIG. 1.

By virtue of the side and end plates 86 and 88 being of a length somewhat shorter than the corresponding plates on the lower section 74 of the outer shell 14, the outer surface portions of the upper section 75 freely fit between the surrounding and adjacent free edges of the webs of the beams 72 of the framework 12, as indicated by the clearance space at 90 in FIGS. 2-2A and 3.

The top of the upper section 75 of the overall outer shell 14 is reinforced by a surrounding box beam assembly 92 connected thereto. The box beam assembly 92 is comprised of four channel-shaped elements 94 and 96 respectively. Each one of the four channel-shaped elements 94 of one series of such elements is of a length corresponding to the length of the opposed side plates 86 of the upper section 75 of the outer shell 14.

Each one of the four channel-shaped elements 96 of the second series is of a smaller configuration in transverse cross section than the channel-shaped elements 94 of the first series. The four channel-shaped elements are also arranged in two pairs in a corresponding fashion so as to form two smaller box beam sections. Each one of the two smaller box beam sections is of a length longer than the length of an end plate 88 of the upper section 75 of the outer shell 14. As indicated in FIGS. 2-2A and 3, the two larger box beam sections comprised of the first series of four channel-shaped elements 94 are aflixed to outside surface portions of opposed side plates 86 of the upper section 75 of the outer shell 14 adjacent the top edge thereof. The smaller two box beam sections made up of the four channel-shaped elements 96 of the second series are aflixed to outside surface portions of the end plates 88 of the upper section of the outer shell adjacent the top edge thereof in such fashion that the upwardly facing back sides of the top webs of the elements 94 in the smaller box beam sections are disposed in planar alignment with the upwardly facing back sides of the top webs of the elements 94 in the two larger box beam sections. At the same time the longitudinal ends of either one of the smaller box beam sections overlap and are connected to adjacent longitudinal ends of the two larger box beam sections of elements 94, thereby forming a rigidfied beam assembly 92, as indicated in FIGS. 22A and 3. If desired, a series of four angle-shaped reinforcing elements 98 may be disposed about and afiixed to the outer peripheral surface portions of the box beam assembly 92, as illustrated in FIGS. 2-2A and 3. Finally, a plurality of four interconnected angle-shaped elements 99 may be aflixed to the outside of the top edge of the upper section 75 of the outer shell 14 above the box beam assembly 92 for reinforcing the upper edge thereof.

Channel-shaped shoe elements 100 corresponding to the number of the beams 72 of the framework 12 are advantageously afiixed to preselected surface portions of the downwardly facing side of the web of the lower beams 94 and 96 of beam assembly 92 in spaced relation to each other in such a fashion that any one of the relatively spaced elements 100 of the series thereof is disposed in alignment with the upper end of its associated beam 72 of the framework 12. In effecting assembly of the upper section 75 of the outer shell 14 to both the lower section 74 thereof and the upstanding beams 72 of the framework 12, the affixed shoe elements 100 are adapted to be aligned with and overlap the upper ends of their associated beams 72 in such a manner that the upper longitudinal end faces of the beams 72 abuttingly engage the downwardly facing web portions of the beams 94 and 96 making up the beam assembly 92. The abutting engagement between the downwardly facing web portions of the beams 94 and 96 and the upper ends of the beams 72 is enhanced by the influence of gravity acting on the overall mass of the upper section of the outer shell 14.

As depicted in FIGS. 2, 2A and 3, shoe elements in overlappingly engaging the upper ends of their associated beams 72 cooperate with these beams during use of the cell 10 to hold outside surface portions of the upper section 74 in spaced relation to the adjacent free edges of the webs of the beams 72 of the framework 12, by the clearance space 90. At the same time, the abutting engagement of the upper longitudinal end faces of the beams 72 with the downwardly facing web portions of the box beam assembly 92 precisely limits the overlapping telescoping engagement of the upper edge of the lower shell segment 74 with the lower edge of the upper shell segment 75, as shown in FIGS. 2-2A and 3.

As indicated in FIGS. 2-2A and 4, each main segment of inner shell 16 is comprised of side plates 102 that form the opposed sidewalls of the longitudinally spaced enlarged portions 21 or legs of the roughly H- shaped overall inner shell 16. Similarly, pairs of side plates 104 of smaller overall size than the plates 102 form the opposed sidewalls of the reduced portions 20, 22 and 24 of the inner shell 16. Each one of the smaller side plates 104 is offset laterally inward of an adjacent sidewall 102 relative to the longitudinal axis of the cell 10. The opposed sidewalls 102 of each one of the pair of enlarged portions 21 and the opposed sidewalls 104 of each one of the reduced portions 20, 22 and 24 are interconnected by shouldered walls 106 that extend in a direction transversely of the longitudinal axis of the cell 10 and are spaced longitudinally therealong in such fashion that any one shouldered wall 106 of a given pair of transversely aligned walls 106 is interconnected at its opposed side edges to the adjacent longitudinal side edges of adjoining and laterally offset sidewalls 102 and 104 on either side of the longitudinal axis of the cell 10 as best shown in FIG. 1.

The outermost longitudinal side edges of the opposed sidewalls 104 of the reduced end portions 20 and 24 at either longitudinal end of the inner shell 16 are interconnected by an end plate 110 that forms a longitudinal end wall thereof. The upper edges of the interconnected side, shouldered and end walls 102 and 104, 106 and 110 making up the inner shell 16 are all aligned as evident from an inspection of FIG. 1.

The overall bottom of the inner shell 16 in transverse cross-section advantageously has an approximate shallow V-shaped configuration similar to the bottom of the outer shell 14. To this end, the lowermost edges of the beveled end walls 110 thereof are interconnected by a centrally disposed bottommost plate 112. The lower beveled edges of each one of the pair of end walls 110 extending between the lowermost edge of each one of the pair of end walls 110 and an opposed side edge thereof are inclined in a direction upwardly and outwardly of their associated lowermost edge on either side of the longitudinal axis of the cell 10. Similarly, the lower edges of each pair of transversely aligned shouldered walls 106 of the four pairs thereof are laterally offset outwardly of the lower beveled edges of the end plates 110 and are beveled in similar fashion on either side of the longitudinal axis of the cell 10. By virtue of the lower edges of the opposed sidewalls 102 of an enlarged portion 21 of the shell 16 being aligned with the outermost lower ends of the shouldered walls 106, the height of each one of the opposed sidewalls 102 of the shell 16 is less than the height of each one of the opposed sidewalls 104 of the reduced portions 20, 22 and 24 thereof. The bottom of the segment of the inner shell 16 includes a pair of inclined plates 114 secured to bottom plate 112. Each plate 114 is comprised of a pair of spaced intermediate enlarged portions and a series of three interposed reduced portions one of which is disposed intermediately of the enlarged portions of a plate 114 and the other two of which are disposed at the outer ends of the enlarged portions thereof. A given plate 114 is of an overall length corresponding to the length of the inner shell 16 between the end walls 110 thereof. The reduced and enlarged portions of the given plate 114 are disposed in alignment with their associated reduced and enlarged portions 20, 22 and 24 and 21 and 21 of the inner shell. Thus, as indicated in FIGS. 1, 2A and 3-4, when each one of the pair of plates 114 is connected to the associated lower side edges of opposed sidewalls 102 and 104, the lower beveled edges of the shouldered and end walls 106 and 110 and to an adjacent longitudinal side edge of the bottom plate 112, the bottom of the inner shell 16 is fully closed off.

Each divider element 28 is generally comprised of a tubular steel sleeve 120 of rectangular shape in transverse section and a baked carbon or graphite block 122 disposed within the opening of the sleeve 120 and extending between the ends thereof. Sleeve 120 can be perforated to facilitate the evaporation of moisture from the carbon block 122 disposed therewithin. One of the purposes of the sleeve is to shield the carbon block 122 during initial heating of the cell 10, particularly prior to the feeding of an electrolytic bath thereto, so as to prevent oxidation thereof.

The top of the inner shell 16 is outwardly flanged at 26 so as to include an upstanding flange 118 interconnecting shoulder 116. Flange 118 and shoulder 116 extend fully about the upper periphery of the inner shell. The shoulder 116 is cut away at various points along the cell periphery so as to define upwardly-facing ledges 124 in the areas of mergence of the main cell segments and the intermediate and end projections 32, 34 and 36. Each transversely aligned pair of ledges 124 is adapted to engage the ends of a divider 28 in order to support the divider 28 disposed therebetween so that its top surface is aligned with the shoulder 116.

The refractory liner 44 circumscribing the top of the inner shell 16 at each one of the enlarged portions 21 thereof is carried by portions of the shoulder 116 and the top surface portions of an adjacent pair of dividers 28 at the longitudinal ends of each one of the enlarged portions 21. As indicated in FIGS. 2A, 3 and 4, the liner 44 is comprised of a plurality of suitably arranged bricks 125 of an appropriate refractory material. By applying a suitable coating to the exposed faces of the bricks, the inner shell 16 can in effect be made impervious to the electrolytic bath 46 and to the chlorine liberated at the surface level thereof.

The upper edge of the inner row of bricks 125 is offset upwardly of the upper edge of the outer row of bricks .125 in each one of the liners 44, as shown in FIGS. 2A, 3 and 4. A strip of refractory material 126 is cast about the offset top edges of the inner and outer rows of bricks 125, thereby locking the strip 126 to the bricks and forming the top edge of a liner 44 to which the cover '50 is sealably connected for closing off the top of an associated electrolytic chamber 40. The combined weight of the cover 50 and the liner 44 in each one of the pair of enlarged portions 21 effectively counteracts the bubbling action of the electrolytic bath 46, thereby maintaining the seal connection between the liner 44 and associated portions of the flange 26 and adjacent pair of dividers 28.

The refractory liner 42 for each one of the reduced portions 20, 22 and 24 of the inner shell 16 at the top thereof is comprised of a suitable refractory material castin-place in conventional fashion. The refractory liner 42 for each one of the longitudinal reduced end portions 20 and 24 is carried by the outer end portions of the shoulder 116 of the flange 26 and a top surface portion of an endmost divider 28 associated therewith as illustrated in FIGS. 2A and 4. Similarly, the refractory liner 42 for the intermediate reduced portion 22 is carried by opposed intermediate portions of the shoulder 116 of the flange 26 and top surface portions of the adjacent pair of dividers 28 associated therewith. Each reduced end portion 20 or 24 of the cast-in-place liners 42 is confined by portions of the flange 26 and by a divider 28 and adjacent end portions of a liner 44 associated therewith. The intermediately disposed liner 42 in being cast-in-place is confined by opposed portions of the flange 26 and by adjacent pairs of dividers 28 and adjacent end portions of the liners 44. The top of each liner 42 extends above the top edges of both the upstanding flange 118 and the pair of refractory liners 44, as illustrated in FIG. 2 and since these liners form extensions of the dividers 28, they act in conjunction with dividers 28 to effectively separate the upper portions of the feed chambers 32, 34 and 36 from the upper portions of the electrolytic chambers 40 and 40. The liners 42 and 44 also effectively prevent corrosive attack of the electrolytic bath 46 at the top of the inner metal shell 16 when the cell 10 is operating.

A series of pairs of opposed elongated slots 131 (see FIG. 2) are provided on opposed sidewalls 102 in each of the enlarged portions 21 of the inner shell 16 and these slots 131 in conjunction with the slots 133 in outer shell 14 receive the cathode plates 56. As noted above, the inner ends of a pair of cathodes 56 are slightly spaced from each other and they are spliced together by splicing bar assembly 58. Splicing bar assembly 58 can include a grooved block 132 with the groove 134 of the block 132 slidably reeciving the splice bar 130. One end of the bar is affixed to one of the cathode plates 56 and the block is atfixed to the opposing cathode plate 56 to complete the circuit therebetween.

The lower offset upper edge of the cathodes 56 is adapted to contact the bottom of the slotted openings 133 in shell 14 when the upper section 75 of the outer shell 14 is telescopingly connected to the lower section 74 thereof and with the beam assembly 92 being in abutting engagement with the upper ends of the beams 72 of the framework 12, as aforedescribed. In order to assure proper abutting engagement of the bottom of an inverted slot 133 with a given cathode 56, the Width of slot 133 is slightly greater than the thickness of the given cathode 56 and the depth of a slot 133 is slightly greater than the height at the lower offset upper edge thereof.

The outer end of a cathode plate 56 is electrically connected by a plurality of lead-in bus-bar strap elements (not shown) to a bus-bar terminal bracket 141 afiixed to opposed sides of the framework 12 at the lower longitudinal ends of a given pair of beams thereof. To facilitate connection of a lead-in strap element (not shown) to the outer end of a cathode 56, the cathode includes a series of apertures as depicted in FIG. 3.

Legs 136 afiixed to the outside surface portions of the bottom plates 112, 114 and 114 of the inner shell 16 act when the inner shell 16 is lowered by a hoist or the like into the upwardly facing open cavity of the lower section 74 of the outer shell 14 to maintain the inner and outer shells 14 and 16 in the proper centered and spaced relationship to each other. After lowering of the inner shell 16 into the lower section of the outer shell 14, the upper section of the outer shell 14, by the action of a hoist or the like, is connected to the upper ends of the beams 72 of the framework 12 and the lower section 74 thereof in such manner that the inverted U-shaped slots 133 of the upper section 74 of the outer shell 14 freely pass over their associated cathode plates. With reference to FIG. 1, a series of holes or bail elements 127 only some of which are shown are provided about the top edge of the inner shell '16 for facilitating attachment ofa cable rig, not shown, in suitable manner in order to effect hoisting of the inner shell into and out of the upwardly facing cavity of the lower section 74 of the outer shell 14. Similarly, a series of holes are provided about the top edge of the upper section 74 of the outer shell 14 for facilitating attachment of a cable rig (also not shown) in order to effect hoisting of the upper section 75 into and out of connection with the lower section 74 of the outer shell '14 and the beams 72 of the framework 12.

After assembly of the upper section 75 of the outer shell 14 to the cell 10, each slot 133 is sealed from the atmosphere by angular flange sealing elements 135 (see FIG. 2). A given pair of angular flange elements 135 are connected to outside surface portions of an opposed sidewall 86 of the upper section 75 and disposed on opposed sides of an outer apertured end of a cathode 56. One leg section of each sealing element 135 includes openings for receiving cap screw assemblies 137 in order to effect attachment of the element 135 to the outside of an opposed sidewall 86 of the upper section 75. In effecting attachment of one leg section of each element 135 to the opposed sidewall 86 of the upper section 75, the other leg section thereof is disposed in sealing engagement with one side of a given cathode 56 at the outer end thereof. The sealing of slots 133 prevents leakage of the powdered alumina 18 disposed in the space between the shells 14 and 16. If desired, the slots 133 can be made long enough so that reinforcing bars 139 can be sandwiched in between the tops of cathode plates 56 and the bottom of the inverted slots 133 in the manner illustrated in FIG. 2.

When the inner shell 16 is disposed within and in spaced relation to shell 14 as aforedescribed, powdered alumina 18 is added to the space between the shells 14 and 16 in a suitable manner and compacted. By virtue of the approximate V-shaped bottoms of the shells 14 and 16, the alumina 18, under the influence of gravity, is sufiiciently and uniformly compacted to a desired mass and density between the shells 14 and 16 in an appropriate fashion. During operation of the cell at an elevated temperature level, the inner shell 16 tends to expand relative to the outer shell 14, particularly along the longitudinal axis of the cell 10. Since the compacted alumina filler 18 is relatively incompressible, this expansion of shell 16 could cause rupture of either shell 14 or 16 unless compensated for. This compensation is effected by the use of resilient upstanding tubes 140 disposed adjacent end walls of shells 14 and 16, as depicted in FIGS. 2A and 4.

Each of the covers 50* includes inwardly directed flange elements anchored in the cast-in-place refractory portions of the covers. A plurality of I-beams 146 extend cross- Wise to and are connected to the cover 50 by means of brackets 148.

Each cover 50 is provided with a series of support blocks 150 which have a fmsto-conically shaped bottom and a cylindrically shaped top. Clips 152, portions of which engage beams 146 and other portions of which engage support blocks 150, are used to secure the blocks 150 to beams 146.

The cover 50 is completed by means of a cast-in-place refractory 144. The refractory wall 144 is disposed within the confines of the opening delineated by the peripheral flange 142 in such fashion that the castable refractory material of the wall 144 is cast about all the blocks 150 between the ends thereof and about the lower flanged ends of the surrounding channel-shaped elements 142, as illustrated in FIG. 1. In casting the Wall 144 appropriate removable cores (not shown) are employed to locate and define a series of three apertures 52 for receiving the three anodes 54, as well as to locate and define at least one opening 64 for exhausting the chlorine which is liberated from the bath 46 during operation of the cell 10.

A cover 50 is hoisted by the usual means onto the top of the cell 10 and into nesting and sealing engagement with the upper surface of the strip 126 of the refractory liner 44 of its associated enlarged portion 21 of the inner shell 16. If desired, a circumscribing rectangular groove 154 can be formed in the top of the strip 126 and a surrounding length of compressible asbestos rope 156 or the like disposed in the groove 154. The rope 156 acts to also sealably connect a cover to the top strip 126 of the associated liner 44. As depicted in FIGS. 2A and 3, each one of the covers 50 may be further sealably connected to the associated refractory strip 126 by packing alumina 18 between the outer periphery of a cover 50 and the top peripheral edge portions of the outer shell 16 and between the adjacent recessed top edge portions of the refractory liners 42 of the adjoining reduced portions 20 and 22 or 22 and 24, as the case may be.

A series of apertured sealing blocks 158 are associated with each aperture 52 of the pair of covers 50. Each sealing block 158 is comprised of a castable refractory wall having an upwardly and outwardly flared opening 160 for sealably receiving an anode 54. The opening 160 is smaller than an aperture 52 of a cover 50. A sealing block 158 is reinforced by means of interconnected braces 162 connected to the outer periphery of the castable Wall thereof. In overall size each block 158 is smaller than the upwardly facing counterbore of its associated aperture 52 of a given cover 50 and it is adapted to be sealably and slidably disposed against the shoulder defining the bottom of the counterbore thereof, as depicted in FIGS. 2A3.

The support assembly for each anode 54 includes opposed channels 164 and a pair of bus-bar elements 168. The bus-bar elements 168 are interposed between the upper end of an anode 54 and the back sides of the webs of the channels 164. Bolt-nut assemblies 166 pass through aligned apertures in the channels 164, the interposed busbar elements 168 and an anode 54, thereby clampingly assembling channels 164 and bus-bar elements 168 to the anode 54. In connecting the pair of channel-shaped elements to an anode 54, the upper flanges thereof are offset upwardly of the top of the anode 54 and bus-bar elements 168, as indicated in FIG. 2A. The bus bars 168 are longer than the channel-shaped elements 164 and extend beyond the opposed sides of the framework 12, as indicated in FIG. 3.

Channel-shaped legs 174 are connected in depending fashion to the longitudinal ends of each pair of channelshaped elements 164 of a support assembly 60 and the upper end of each leg 174 includes a flange 176. An angleshaped strap element 178 extends across the top flanges of a pair of channel-shaped elements 164 at either longitudinal end thereof. A strap element 178 and a depending leg 174 are clampingly connected to the flanges at either longitudinal end of a pair of channel-shaped elements 164 by a pair of bolt-nut assemblies 180 passing through aligned apertures in the outer ends of both the strap element 178 and the upper flange 176 of the leg 178. In clampingly connecting a pair of the legs 174 to the longitudinal ends of a pair of channel-shaped elements 164 of a support assembly 60, the lower end of the legs are aligned with opposed longitudinally extending sides of the framework 12 of the cell 10 at the top of the box beam assembly 92. Thus a given support assembly 60 and an anode 54 after attachment to the support assembly 60 can be hoisted as a unit to the top of a cover 50 for connection thereto in such manner that the lower free end of the anode 54 is lowered through the aligned apertures and 52 of a sealing block 158 and the cover 50 and into the electrolytic chamber 40 disposed beneath the cover until the lower ends of the legs 174 of the given support assembly 60 abuttingly engage the top of the box beam assembly 92. At this time the lower end of the anode 54 is disposed between adjacent pairs of cathodes 56 in spaced and operative relation thereto as depicted in FIG. 4. By virtue of a given support assembly 60 having its spaced legs 174 in nesting engagement with the box beam assembly 92 and by virtue of the anode 54 being disposed freely in an aperture 52 of a cover 50, the anode 54 is free to move relative to the cell 10 during operation thereof, thereby preventing breakage of the anode 54.

The longitudinal ends of bus elements 168 associated with a support assembly 60 are connected to a DC. source (not shown). A plurality of bus-bar terminal brackets 172 are connected to beams 72 intermediate the ends thereof on opposed sides of the framework 12. The longitudinal ends of bus-bar elements 168 of a support assembly 60 are electrically connected to a pair of brackets 172 by a pair of lead-in strap elements (not shown). Brackets 172 are electrically insulated from the framework 12 and the cathodes 56 by a series of insulating strips 170. Since the pair of legs 174 of a support assembly 60 are electrically connected to the framework 12, a pair of strips 182 are used to electrically insulate a leg 174 from its associated support assembly 60 at either end thereof. One of the insulating strips 182 is interposed between the strap 178 and the top of the upper flanges of the channel-shaped elements 164 of a support assembly 60 at either end thereof as indicated in FIGS. 2-2A and 3. The other strip 182 is interposed between the flange 176 and the bottom of the lower flanges of the channel-shaped beams 164 of the support assembly 60 at either end thereof. If desired, a spacer element 184 can be interposed between the bottom flanges of a pair of channel-shaped elements 164 and the associated insulating strip 182 adjacent the upper flange 176 of the leg 174. The brackets 172 in being afiixed to the beams 72 on opposed sides of the framework 12 are advantageously spaced relative to the outer ends of the cathodes 56 so as not to interfere with the connection and disconnnection of the outer and inner shells 14 and 16 of the cell to the framework 12 thereof as indicated in FIGS. 2-3.

In order to prevent excessive burning of the anodes 54 during operation of the cell 10, a water cooling device 62 or the like can be aflixed to at least one of the channelshaped elements 164 of the support assembly 60. With reference to FIGS. 6-7, the cooling device generally comprises a channel-shaped cover 186 of a longer length than the channel-shaped elements 164. The flanged ends of the cover 186 are indented inwardly and downwardly to facilitate their attachment to the flanged ends of an associated channel-shaped element 164. Appropriate bolt assemblies 188 securely attach the cover 186 to the associated channel-shaped element 164. The longitudinal ends of cover 186 include appropriate inlet and outlet fittings 192 and 194 for connection to an external water source, not shown. To facilitate extraction of heat from an anode 54, a series of spaced fins 190 can be aflixed to the outwardly facing surface of a web of a given channel-shaped element 164 of a support assembly 60, as shown in FIGS. 6-7.

Feed chambers 32, 34 and 36 are covered by an apertured plate 66 that extends between the upper edges of the outer shell 16 and the adjacent side portions of a cover 50 or adjoining covers 50, as the case may be, in the manner shown in FIGS. 2-2A and 4. A cover 198 can be hingedly connected to the plate 66, thereby covering the aperture thereof.

In an operative embodiment of the cell 10 of the instant invention, the cell 10 with the anodes 54 initially removed can be heated up to an operating temperature on the order of 1300 to 1500 F. Then the fused electrolytic bath 46, containing magnesium chloride and having a density less than the magnesium metal produced thereby, can be added to the heated cell 10. One suitable electrolyte that can be used is that set forth in the US. Pat. 2,950,236 to Dean et al. granted on Aug. 23, 1960. Appropriate gas-type and electrical heaters, not shown, can then be inserted through the openings of the feed chambers 32, 35 and 36 and the apertures 52 of both cover elements 50. When the cell 10 is brought up to an operating temperature and after adding the electrolyte 46 until its surface level is between the top and bottom of the refractory liners 42 and 44 in the manner shown in FIG. 1, the cell 10, by virtue of the powdered alumina 18, can be maintained at an optimum operating temperature of about 1400 F. by merely having the heaters, not shown, disposed in the openings of the feed chambers 32, 34 and 36, thereby keeping the electrolyte 46 in the molten state. At this time, the anodes 54 and their associated support assemblies 60 are connected to the cell 10. After connection of the anodes 54, the DC. source, not shown, is connected to the cell 10, and the heaters removed. Then the cell 10 will continue to operate to produce magnesium that settles to the bottom of the inner shell 16 and liberates gaseous chlorine from the bath 46 at the top of the electrolytic chambers 40 and 40. The gaseous chlorine is removed through the opening 64 for subsequent processing, and the magnesium metal is removed periodically from the feed chambers 32, 34 and 36 in an appropriate manner, for example, by piping, not shown, connected to the bottom of the inner shell 16. The feed chambers 32, 34, 36, by virtue of the dividers 28 and refractory liners 42 and 42, enable the electrolytic bath 46 to be replenished during operation of the cell without interfering with the electrolytic bath producing chlorine and magnesium metal in the electrolytic chambers 40. In replenishing the bath 46 with a magnesium chloride feed, it may even be hydrated since the bath 46 in being at an elevated temperature during operation of the cell 10 will effect dehydration of the magnesium chloride feed before it circulates to the electrolytic chambers 40.

By virtue of the cell 10 of the instant invention being constructed in the manner aforedescribed, access to selected interior portions of the cell 10 may be readily obtained for normally servicing certain parts thereof, such as repair or replacement. The powdered alumina 1'8 disposed in the space between the shells 14 and 1 6 may be selectively removed by an appropriate suction device (not shown) in vacuum cleaner fashion thereby enabling access into the space between the shells. If it is desired to remove one or more support assemblies 60 with their anodes 54, the bus-bars 168 associated with the anodes 54 are discon nected from their associated bus-bar terminals 172, thereby electrically disconnecting anodes 54 from the D.C. source (not shown). During removal of the support assemblies 60 with their anodes 54, the bath 46 within the inner shell 16 may be maintained at operating temperature by auxiliary gas heaters (not shown) wherein the gas heaters (not shown) are inserted through an anode open ing 52 or a feed opening 32 or 34 or 36 in a cover 198 of the inner shell 16.

If it is necessary to remove the upper section 75 of the outer shell 16 in order to service the cell 10, a substantial part of the powdered alumina 18 must be removed as well as all the support assemblies 60 with their anodes 54. After Withdrawing the angular members from engagement with their associated cathode element 56 by loosening of the cap screw assemblies 137 in conventional fashion, the upper section 75 of the outer shell 14 can be disconnected from the lower section thereof and the beams 72 of the framework 12 by a suitable hoist connected to the holes at the top of the upper section 75 thereof.

The inner shell 16 after removal of the upper section 75 of the outer shell 14 can be disconnected from the lower section 74 of the outer shell 14 by use of a suitable grapple device having hooks insertable in the holes at the top thereof. Prior to hoisting the inner shell 16 out of the outer shell, the auxiliary gas heaters (not shown) are withdrawn from the inner shell 16. -At the same time, the cathodes 56 are disconnected from their associated bus-bar terminals 141, thereby electrically disconnecting the oathodes 56 from the DC. source (not shown). Thus, except for removal of the inner shell 16, the overall cell may be serviced without interfering with the operation thereof.

Depending upon the capacity of the cell 10, it should be understood that only one anode and cathode may be required as well as only one feed chamber and one electrolytic chamber wherein the chambers are partially separated by a divider. Further, the anodes and cathodes could be cylindrical instead of rectangular as shown. Although the refractory liner 44 is comprised of refractory bricks 125, the liner 44 could be comprised of a suitable cast-inplace refractory material. It is to be understood that even though the cell 10 of the instant invention has been described with reference to use of an electrolytic bath having less density than the magnesium metal produced, it is not to be limited thereto. By virtue of the grid-like framework 12, the cell 10 can be constructed above or below a floor level. Depending upon the construction of the outer shell 14 for a given installation of cell 10, the outer shell may be made sufliciently strong enough to obviate the use of a separate framework 12 for supporting the same.

The removable filler is preferably powdered alumina 1'8, but it is to be understood that any suitable filler material can be used, for example, a granular material or a fluid material or even a solid material such as magnesia brick. Regardless of the removable filler material used, it should have suflicient strength to withstand the forces exerted thereon during operation of the cell 10 and the elevated temperatures at which the cell 10 is operated.

A preferred embodiment of the cell of the instant invention which is made up of readily removable and replaceable parts has been specifically illustrated and described, and it will be understood that the invention is not to be limited thereto, as many variations will be apparent to those skilled in the art and the invention is to be given its broadest interpretation within the terms of the following claims, wherein:

What is claimed is:

1. An electrolytic cell for producing magnesium metal and the like, said cell comprising a pair of open ended shells one of which is nested within and at least partially spaced from the other, and means for telescopingly connecting the upper section of the outermost shell to the lower section thereof, said inner shell comprising a bottom and upstanding sidewalls for holding the electrolyte, and containing at least one anode and at least one cathode.

2. An electrolytic cell as set forth in claim 1, including means interposed between said inner and outer shells and compensating for the thermal expansion of the inner shell relative to the outermost shell so as to prevent fracture of either one of the shells.

3. An electrolytic cell as set forth in claim 1 in which said shells are comprised of a ferrous metal.

4. An electrolytic cell as set forth in claim 1, wherein the walls of said shells are provided with sealable openings for receiving at least one cathode element.

5. An electrolytic cell as set forth in claim 1, wherein the cathode element comprises segments connected together so as to maintain alignment of said cathode element segments during operation of said cell.

6. An electrolytic cell as set forth in claim 1 in which the top of said inner shell is provided with a sealable cover means.

'7. An electrolytic cell as set forth in claim 1 including divider means extending between and connected to opposite sidewall portions at the upper part of said inner shell, said divider means acting in conjunction with the electrolyte in the cell in order to isolate gases generated during operation of the cell from an electrolyte feeder opening.

8. An electrolytic cell as set forth in claim 1, including a removable cover provided for floatably and sealably suspending the anode within the inner shell.

9. An electrolytic cell as set forth in claim 1, including means for cooling the anode.

10. An electrolytic cell as set forth in claim 1, including stop means on the upper section of said outermost shell for limiting the telescoping connection between the upper and lower sections of said outermost shell.

11. An electrolytic cell as set forth in claim 1, in which one of the shells is provided with fixed leg means attached to the bottom thereof for engaging the associated portion of the other shell so as to maintain the shells in spaced relation to each other.

12. An electrolytic cell as set forth in claim 1 including a filler material disposed in the spaces between the shells.

13. An electrolytic cell as set forth in calim 12 in which said filler material is powdered alumina.

14. An electrolytic cell for producing magnesium metal and the like, said cell comprising a pair of open ended shells one of which is removably nested within and at least partially spaced from the other, the upper section of the outermost shell being telescopingly connected to the lower section thereof to provide ready access to the inner shell during removal of the inner shell from or installation of the same within the outer shell and filler material removably disposed in spaces between said shells.

15. A cell as set forth in claim 14 wherein the bottom portions of the said shells have converging sidewall portions for facilitating the settling of the filler material in the spaces between the respective shells.

16. A cell as set forth in claim 14 including leg elements on one of the shells and engageable with the other shell for holding at least portions of the shells in spaced relation to each other.

17. A cell as set forth in claim 14 wherein the top sections of the shells are provided with sealable openings for receiving at least one cathode element.

18. A cell as set forth in claim 17 wherein the opening in the upper section of the outer shell is in the form of a downwardly opening slot.

19. A cell as set forth in claim 14 including divider means extending between and connected to opposite side wall portions of the upper part of the inner shell, said divider means acting in conjunction with the electrolyte in the cell during its operation to isolate gases generated during said operation from an electrolyte feeder opening.

20. A cell as set forth in claim 14 including an anode and cooling means for the anode.

21. An electrolytic cell as set forth in claim 14. wherein the filler material is powdered alumina.

22. A cell as set forth in claim 14 including means interposed between said shells for compensating for the thermal expansion of the inner shell relative to the other shell so as to prevent fracture of either one of the shells.

23. A cell as set forth in claim 14 wherein the inner shell is of a greater height than the lower section of the outermost shell and said inner shell being provided with means engageable with a hoisting device.

References Cited UNITED STATES PATENTS 2,355,761 8/1944 Upton 204243 2,861,036 ll/ 1958 Simon-Suisse 204243 3,494,851 2/ 1970 Cauvin, J r 204243 3,514,520 5/1970 Bacchiega et a1. 204243X JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 204-70, 245 

